If you remove the fabric softener, sometimes you find something there. You want to try this first.
You can more often find small items like earings in the water pump. This is located inside the machine. The drain hose is attached to it. Remove the cabinet to access the inside and check inside of the pump from the washer side. There is filter on that side.
You probably want to do this because eventually these things can cause damage to the machine.
Yes, that is the thing that sits in the middle of the agitator. Remove that and check inside.
To access the inside of the washer - There are two screws on the front bottom (one on each side) that you remove. The front panel should come straight out and right off.
Be careful so that you do not remove or damage the clips on the top of the cabinet.
When the front comes off you should be able to access the pump on the back left side. You want to remove the hose that goes into and check that opening. If not found there you may have to remove the pump also.
However, (depending on the pump) I don't reccommend that you dissassemble the pump.